linux-kernel - Re: [PATCH v7 2/6] vfio/type1: Check reserve region conflict and update iova list

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Date:   Fri, 5 Jul 2019 14:09:30 +0200
From:   Auger Eric <eric.auger@...hat.com>
To:     Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>,
        Alex Williamson <alex.williamson@...hat.com>
Cc:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        Linuxarm <linuxarm@...wei.com>,
        John Garry <john.garry@...wei.com>,
        "xuwei (O)" <xuwei5@...wei.com>,
        "kevin.tian@...el.com" <kevin.tian@...el.com>
Subject: Re: [PATCH v7 2/6] vfio/type1: Check reserve region conflict and
 update iova list

Hi Shameer,

On 7/4/19 2:51 PM, Shameerali Kolothum Thodi wrote:
> 
> 
>> -----Original Message-----
>> From: kvm-owner@...r.kernel.org [mailto:kvm-owner@...r.kernel.org] On
>> Behalf Of Alex Williamson
>> Sent: 03 July 2019 21:34
>> To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>
>> Cc: eric.auger@...hat.com; pmorel@...ux.vnet.ibm.com;
>> kvm@...r.kernel.org; linux-kernel@...r.kernel.org;
>> iommu@...ts.linux-foundation.org; Linuxarm <linuxarm@...wei.com>; John
>> Garry <john.garry@...wei.com>; xuwei (O) <xuwei5@...wei.com>;
>> kevin.tian@...el.com
>> Subject: Re: [PATCH v7 2/6] vfio/type1: Check reserve region conflict and
>> update iova list
>>
>> On Wed, 26 Jun 2019 16:12:44 +0100
>> Shameer Kolothum <shameerali.kolothum.thodi@...wei.com> wrote:
>>
>>> This retrieves the reserved regions associated with dev group and
>>> checks for conflicts with any existing dma mappings. Also update
>>> the iova list excluding the reserved regions.
>>>
>>> Reserved regions with type IOMMU_RESV_DIRECT_RELAXABLE are
>>> excluded from above checks as they are considered as directly
>>> mapped regions which are known to be relaxable.
>>>
>>> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>
>>> ---
>>>  drivers/vfio/vfio_iommu_type1.c | 96
>> +++++++++++++++++++++++++++++++++
>>>  1 file changed, 96 insertions(+)
>>>
>>> diff --git a/drivers/vfio/vfio_iommu_type1.c
>> b/drivers/vfio/vfio_iommu_type1.c
>>> index 970d1ec06aed..b6bfdfa16c33 100644
>>> --- a/drivers/vfio/vfio_iommu_type1.c
>>> +++ b/drivers/vfio/vfio_iommu_type1.c
>>> @@ -1559,6 +1641,7 @@ static int vfio_iommu_type1_attach_group(void
>> *iommu_data,
>>>  	phys_addr_t resv_msi_base;
>>>  	struct iommu_domain_geometry geo;
>>>  	LIST_HEAD(iova_copy);
>>> +	LIST_HEAD(group_resv_regions);
>>>
>>>  	mutex_lock(&iommu->lock);
>>>
>>> @@ -1644,6 +1727,13 @@ static int vfio_iommu_type1_attach_group(void
>> *iommu_data,
>>>  		goto out_detach;
>>>  	}
>>>
>>> +	iommu_get_group_resv_regions(iommu_group, &group_resv_regions);
>>
>> This can fail and should have an error case.  I assume we'd fail the
>> group attach on failure.  Thanks,
> 
> Right. I will add the check. Do you think we should do the same in vfio_iommu_has_sw_msi()
> as well? (In fact, it looks like iommu_get_group_resv_regions() ret is not checked anywhere in
> kernel). 

I think the can be the topic of another series. I just noticed that in
iommu_insert_resv_region(), which is recursive in case ot merge, I
failed to propagate returned value or recursive calls. This also needs
to be fixed. I volunteer to work on those changes if you prefer. Just
let me know.

Thanks

Eric
> 
> Thanks,
> Shameer
> 
>